Technical Chevy straight-six folks: 261 or 292?

This is really interesting. I'd love to know more about how this was done.

 

Thanks to everyone for all the input! A local reader made us an offer we couldn't refuse on this 292 and some ancillaries. If I'm decoding it right, it's from a 1980 Chevrolet C20 (which meshes with the seller's story of pulling it from an early '80s dually). We got it to start and run. It doesn't knock, so we're going to pull it apart and freshen it up. Cross your fingers we don't discover anything weird!



I also ran the numbers on our engine with the cracked block. It's from 1964, which means there could potentially be a forged crankshaft in there. On the other hand, it's wearing a head with plugged smog holes and was supposedly in a 1966 C60 truck, so it's probably some mismatched old rebuild.

 

1980 is about the time GM had the blocks cast in Mexico, which are the more desirable ones. It will say cast in Mexico on the block if so.

 

If you want to know more about the engines origins, post pictures of the stamped numbers near the distributor, and the casting numbers and casting dates near the starter. We can help figure it out.

 

It does.

@squirrel I'll post up those pictures later on. I'm on deadline for some other things but I wanted to put a little update here while I took a break.

 

292 = 7 main bearings
261 = 4 main bearings

 

Just me but I'd put an Oldsmobile V8 engine in it.

 

Small block Chevy, HRP

 

Stamped number on the running engine appears to be M0512TSA.


Cast number on the running engine is 93406004 (plus Hecho en Mexico).


Stamped number on the old engine is F0124PG.


Cast number on the old engine is 3851659.

 

292s were scarce back in the '70s; i'd go with the 250. if you're interested, i have a 20,000-mile mallory "dual life" distributor i'd donate to the cause...

 

thanks for the pics

The casting date code on the black 292 is hard to read, it's hidden by the diptsick and a layer of grease, but looks like it ends with 81? The format is Month Day Year. Month is a letter A-L, Day is a number 1 to 31, Year is a number either the last digit or last two digits of the year. I don't have a book with truck numbers after 1972 unfortunately, to look up TSA.

The blue 292 is a 64 engine from the PG code and the casting date code ending in 4

 

I'm heading into the office later this afternoon. I'll try to get a better image of the running 292's date code. Thanks for the information so far.

 

I have a Canadian '57 Pontiac with a 261 it came (Canada) factory with the "848" head and a cam with a very similar grind to the early Corvette Blue Flame except hydraulic....you might want to look up here if you decide on the 261...that being said my vote (if it were available) would be full house 302 Wayne, Horning, Clifford etc etc etc with the stock wheels! a) you only live once b) it's not original anymore anyway ....I just imagine everyone expecting some stock 250 painted grey, w dummy external oil filter/oil bath air cleaner dressed up to look like the stock engine...yawn!
I see the most jewel laden eye candy 302...it would be outtasight!